Beverage preparation device with in-line scale removal system and descaling method using such system

ABSTRACT

Beverage preparation machine comprising: a fluid circuit comprising a water reservoir, a water pump, a heating means, a beverage producing module, which are fluidically connected for circulating water from the reservoir to the beverage producing module, wherein an inline descaling system is provided in the fluid circuit comprising a dedicated compartment intended for receiving a predetermined dose of a water soluble/dispersible descaling agent. The invention also relates to a method for automatically descaling and rinsing the fluid circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/936,497 filed Oct. 5, 2010, which is a continuation of Internationalapplication PCT/EP09/050902 filed Jan. 28, 2009, the entire content ofwhich is expressly incorporated herein by reference thereto.

DESCRIPTION

The present invention relates to a beverage preparation machine designedwith a scale removal system for removing the limestone scale thatsettles on the fluid contact surfaces of the machine. The invention alsorelates to a method for automatically removing limestone scale in abeverage preparation device using this system.

BACKGROUND

It is a well known problem with any beverage producing device having anintegrated heater, e.g., a thermoblock or heating cartridges, thatlimestone scale is prone to deposit on the heating/heated contactsurfaces with the circulated water or steam. The water scale comesessentially from water insoluble solid, i.e., calcium carbonate thatformed from calcium ions and carbonate ions which react together andprecipitate. The deposition increases in hot water because calciumcarbonate is less soluble in hot water than in cold water. Therefore,the degree of deposition of calcium carbonate solid can be dependent onthe content of these ions in water, also called “water hardness” butalso on the water temperature, the frequency of use of the machine, andother factors.

To descale the beverage preparation machine, it is known to periodicallyhave a decalcifying agent be passed through the water contact surfacesof the fluid circuit of the machine, e.g., heaters, tubings, water/steaminjecting nozzle or needles, etc. The descaling agent (e.g., a chemicalcomposition comprising acetic acid, phosphoric acid and/or a phosphonicacid) dissolves the scale that forms on the surfaces of the machine.After having passed the descaling agent, it is necessary to have acertain volume of clear water be circulated in the fluid circuit of themachine to eliminate taste perceptible trace of descaling agent that mayaffect the taste of subsequently produced beverages.

Therefore, a typical procedure for descaling a beverage producingdevice, e.g., a coffee machine, consists in mixing an effective dose ofdescaling agent with water in the water reservoir of the machine to forma descaling aqueous mixture, circulating the descaling aqueous mixturein the fluid circuit of the machine, rinsing the fluid circuit withclear water filled into the reservoir when the effective descaling agenthas been fully circulated. This procedure requires several manualoperations and a periodic surveillance from the user who achieves thesedifferent operations. In particular, the user must fill the reservoirwith water twice, collect and also discard the liquid waste twice at thecollecting side of the machine, i.e., at the beverage discharge outlet.This also requires several switches-on/switches-off on the board forcontrolling by the pump the circulation of water. Therefore, it isfastidious for the user to stay in front of the machine until thedescaling procedure is completed. Another problem comes from adifficulty to control the effective quantities of the descaling agentand of the rinsing liquid. Therefore, the effectiveness of the methodhighly depends on the respect of these quantities by the user himself.

W02006/090183 relates to a beverage dispenser comprising aclean-in-place system wherein the cleaning fluid is pumped from astorage area to the beverage line. The cleaning operation is carried outautomatically in response to a predetermined event. However, thecleaning agent is not directly placed in the beverage line and it sorequires to be pumped in the beverage line by pumping means.

Therefore there is an advantage to propose a solution that eases thedescaling procedure, in particular, makes it simpler to use, requiresless attention from the user and is also better controlled for animproved descaling efficiency.

For this, the invention relates to a beverage preparation devicecomprising:

a fluid circuit comprising a water reservoir, a water pump, an in-lineheating means designed for heating circulating water, a beverageproducing module, which are fluidically connected for circulating waterfrom the reservoir to the beverage producing module, wherein an in-linedescaling system is provided in the fluid circuit downstream of thereservoir, comprising a dedicated compartment arranged for receiving apredetermined dose of a water soluble/dispersible descaling agent and awater inlet and water outlet for water to circulate through thecompartment.

Therefore, a dedicated descaling agent reserve is arranged in the fluidcircuit, downstream of the water reservoir, so that a predeterminedquantity of water of the water reservoir can be utilized both fordescaling purpose and for rinsing purpose. This arrangement is such thatthere is no need to refill the water tank with clear water since thewater thank is not directly contaminated with the descaling agent.

In a mode, the compartment is fluidically placed between the waterreservoir and the pump. In particular, a one-way valve is interposedbetween the water reservoir and the compartment; wherein the valve isallowed by design or actively controlled to open only when water isdrawn from the water reservoir to the compartment, e.g., by suctioneffect of the pump which opens the valve.

Therefore, a back-flow of the descaling agent in the reservoircontaining clear water can be prevented when the pump is stopped, forinstance, during pause(s) in the descaling procedure. Therefore, thecontinuous descaling-rinsing procedure can be carried out successfullywithout intervention from the user for rinsing or refilling the watertank. The one-way valve can be a passive valve such as a rubber-elasticslit valve or such as a ball spring-biased valve. The one-way valve canalso be an electromagnetic valve controllable in opening/closing by thecontrol unit of the device. The valve can be placed in a wall thatseparates the water reservoir from the descaling compartment. The wallcan advantageously be the bottom wall of the water reservoir and/or anentry wall of the compartment.

In a particular mode, for reducing the complexity of the device, thereservoir and the compartment can be placed adjacent one another. Forexample, the compartment and the reservoir have complementary stackingmeans for enabling the reservoir to be stacked on the compartment. Watersealing means can further be provided between the stacking means.Sealing means can be an O-ring of rubber elastic material.

In a possible alternative solution, the compartment is placed betweentwo portions of hose and fluidically distant from the water reservoir.

In a possible embodiment, the compartment for the descaling agent isfluidically placed between the pump and the in-line heating means. Inthis case, the compartment and its connections to the fluid circuit mustresist to the fluid pressure exerted in this pressurized portion of thefluid circuit to the repeated beverage brewing and descaling cycles.

SUMMARY

According to an aspect of the invention, the beverage preparation devicecomprises a control unit and a control command for controlling thecirculation of a predetermined quantity of water from the reservoir inthe fluid circuit. The control unit further comprises at least oneprogram designed for automatically controlling the activation of thepump as a response to the activation of the control command to circulatethe predetermined quantity of water in the fluid circuit.

A predetermined quantity of water to be circulated can be controlled bythe control unit on any one or more of the following control schemes:

timing of the pump electrical supply,

filling level sensing in the water reservoir

water volume sensing by a flow meter and/or

sensing the acidity level in the fluid circuit.

The descaling agent can be a water soluble/dispersible sachet ornon-soluble/non-dispersible porous sachet containing a watersoluble/dispersible descaling substance, a tablet made of a solid watersoluble/dispersible descaling substance, granules of a solid watersoluble/dispersible descaling substance or a liquid descaling substance.

The compartment for the descaling agent can also be a removablecartridge of the device which contains a predose of descaling agent. Inthis case, the cartridge can be designed as a single-use cartridge whichis recycled or thrown away after use in the device. The cartridge mayalso be designed to be refillable by a dose of descaling material.

The device and the descaling agent can form together a kit.

The present invention further comprises a method for descaling abeverage preparation machine automatically under the control of acontrol unit of the machine, wherein it comprises, after the userplacing a dose of descaling agent in the compartment and filling thereservoir with a predetermined quantity of water:

circulating a first part of the predetermined quantity of water from thereservoir, in the fluid circuit, whereby the descaling agent isdissolved or dispersed progressively by water passing through thecompartment to form descaling liquid circulating through the heatingmeans,

automatically circulating a second or remaining part of the saidquantity of water from the reservoir in the fluid circuit through theheating means after the descaling agent has dissolved or dispersed inthe compartment to rinse the said fluid circuit.

The circulation of the first and second parts of the predeterminedquantity of water is commanded by the control unit which activates thepump automatically on and off.

The first and second parts of said quantity of water are automaticallysequentially circulated upon the user activating a descaling procedure'scommand and according to a descaling program of the control unit,without requiring intervention of the user.

The total quantity of water in the reservoir is determined as a functionof the dissolvability/dispersability of the descaling agent so that asecond or remaining part of said quantity of water can be circulated torinse the fluid circuit after the descaling agent has been removed fromthe compartment. The quantity of water can be materialized by a visualindicator of level in the reservoir and/or can be sensed electronicallyby the control system and used in the descaling program of the controlunit for managing the activation of the pump.

According to an aspect of the invention, the first quantity and secondquantity of water are circulated sequentially automatically upon theuser activating a descaling procedure's command and without any moreintervention of the user. In other words, it means that the control unitof the machine is programmed in such a way that the second quantity ofwater for rinsing purpose is circulated, automatically after the firstquantity of water, without requiring intervention to activate therinsing phase or for refilling the reservoir unless, eventually, aninsufficient quantity of water is detected in the water reservoir and/orthe fluid circuit is empty of water.

An insufficient level of water in the water tank can be detected by awater sensor placed in the water tank for instance. Similarly, a lack ofwater in the fluid circuit can be detected by a flow meter or anyequivalent sensing means.

Therefore, the descaling and rinsing phases can be programmed in thecontrol unit of the device to operate automatically, for example, as aresponse of the activation of a command (e.g., a push of a button orpressure on a touch screen).

The method can comprise a programmed operation during which the waterlevel in the water tank is sensed, e.g., by a water level sensorassociated to the reservoir, to verify that the reservoir is filled withthe predetermined quantity of water necessary for the descalingprocedure. As part of this program, the descaling procedure can beinterrupted, e.g., the water pump is not started, if the quantity ofwater sensed in the reservoir is lower than the predetermined quantityof water. The interruption of the descaling procedure can be maintainedas long as the predetermined water quantity in the reservoir is notreached. This would so require the user to fill the reservoir with thepredetermined quantity of water.

The descaling program may also comprise an operation for which theacidity level of the water in the fluid circuit is sensed, e.g., by anin-line pH probe associated to the fluid circuit, to verify the level ofrinsing of the fluid circuit before ending the descaling procedure,e.g., stopping the water pump.

Other verifications may be envisaged in a descaling program stored inthe control unit of the beverage preparation device such as the presenceof the collecting recipient under the beverage outlet to collect thedescaling and rinsing liquid such as by a light sensor or a mechanicalswitch.

For an improved descaling efficiency, during the descaling procedure,one or more pause can be allowed during which descaling liquid remainspresent in the fluid circuit. For instance, the pause can be programmedto last from 10 seconds to 20 minutes. The pause(s) is (are) controlledby the control unit momentarily stopping the water pump during thedescaling phase.

As aforementioned, for the descaling procedure the dose of descalingagent and the quantity of water in the reservoir are determined so thata sufficient part of said quantity of water is circulated from thereservoir to the module after the descaling agent is entirely dissolvedor dispersed to rinse the fluid circuit. For example, about from ⅓ to ⅔of the initial quantity of water is circulated from the reservoir forthe rinsing purpose when the descaling agent is entirely dissolved ordispersed.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of the main components of a beveragepreparation device of the invention,

FIG. 2 is a partial cross-sectional view showing a detail of thedescaling system in the fluid circuit of the device,

FIG. 3 is an even larger detail in cross-sectional view of the descalingsystem of FIG. 2 when water is not circulated,

FIG. 4 is the same detail as in FIG. 3 but when water is circulated,

FIG. 5 shows a graph illustrating the quantity of water circulated inthe fluid circuit as a function of time and simultaneously the quantityof descaling agent dissolved or dispersed as a function of time,

FIG. 6 is a view of a variant of the beverage preparation device withthe descaling system,

FIG. 7 is a flow chart illustrating a simple descaling procedureaccording to the invention,

FIG. 8 is a flow chart illustrating a descaling procedure of theinvention including a control of the water level in the reservoir,

FIG. 9 is a flow chart illustrating a descaling procedure of theinvention including a control of the water in the fluid circuit,

FIG. 10 is a flow chart illustrating a descaling procedure of theinvention with a pH level control of the water in the fluid circuit.

DETAILED DESCRIPTION

In FIG. 1, a beverage preparation device is shown, for example, a coffeemachine 1 which comprises different essential components forming a fluidcircuit 2 and a built-in descaling system 3 according to the principleof the invention. The machine typically comprises a water supply whichcan be a reservoir 4. The water reservoir is in fluid communication witha water transport means, i.e., a pressure pump 5 via a first portion ofhose 6. The pump itself is in fluid communication, at downstream, withan in-line heating assembly such as a thermoblock 7. The pump 5 and thethermoblock 7 can be linked by a second portion of hose 8. A flow meter50 can be placed in the fluid circuit to sense the flow rate of theliquid circulating in the circuit. Downstream of the thermoblock 7, abeverage production module 9 is provided which receives the heated waterfrom the thermoblock via a third portion of hose 10. A control unit 11is provided to control the switching of the pump and of the thermoblock.A keyboard 12 is also provided which communicates several selectivecommands to the control unit including an electric supply on/off command13, beverage commands 14 and a command 130 for the descaling procedurefor running the descaling procedure. Certain commands can be simpleswitches or interactive visual symbols on a touch screen forming, insuch case, the keyboard or any equivalent command indicators.

In the present invention, the different components of the device in thefluid circuit can take different configurations without departing fromthe scope of the invention. For instance, the water supply can bereplaced by a water connection means able to plug to a domestic watertap. The water transport means can be a pressure pump such as a solenoidpump that provides high static pressure for the preparation of espressocoffees. However, it may also be any other types of pumps such as aperistaltic pump or a membrane pump.

The water heater 7 may be a thermoblock or other types of in-line heaterwhich heats a circulating liquid such as heating cartridges withceramic-coated heating elements or a tubular thick film heater. Thebeverage preparation module 9 can be designed to receive a controlledportion of beverage ingredients in the form of capsules, pods or sachetswhich are brewed by hot water passing through the ingredients at acertain controlled pressure. The module could also be associated to amilling system and so designed to receive directly a ground portion ofingredient in a brewing chamber of the device. The beverage is collectedby a beverage outlet 14.

A preferred in-line descaling system 3 is proposed in FIGS. 1 to 3 whichmore particularly comprises a dedicated compartment 15 designed forreceiving a descaling agent. The compartment is preferably fluidicallyplaced between the water reservoir and the water pump, i.e., in the lowpressure portion of the fluid circuit. In particular, the systemcomprises a water inlet 70 for water to enter the compartment and awater outlet 71 for water to leave the compartment. The compartment isdimensioned to receive a dose of descaling agent, e.g., of volumebetween 20 and 250 Ml.

In a preferred design, the compartment is placed below the waterreservoir in a stacking configuration in order to facilitate the openingof the compartment and the placing of the decaling agent.

Therefore, the compartment comprises a cup-shape element and an upperwall of the compartment which is defined by the bottom wall 21 of thereservoir. The upper wall comprises the water inlet 70 of the descalingsystem. Therefore, water can transfer directly from the reservoir to thecompartment without tubing. The bottom wall of the cup-shaped element ofthe compartment comprises the outlet 71 which is connected to theportion of hose 6 of the fluid circuit via a short duct portion forinstance.

The reservoir and the compartment comprise complementary stacking means16. For instance, the compartment comprises an enlarged portion of wall17 which receives a base portion 18 of the reservoir. The base portion18 of the reservoir can thus inserts itself in the enlarged portion ofthe compartment by simple press-fitting engagement. Water sealing means22 can be placed between base portion 18 and the enlarged portion 17 ofthe compartment. The sealing may be a rubber O-ring or a similar means.Therefore, when the reservoir is lifted by the user, the compartment isuncovered and can be loaded with a dose 19 of the descaling agent.

A one-way valve 20 is preferably placed fluidically between thereservoir and the compartment, for instance, at the bottom wall 21 ofthe reservoir. The valve acts to ensure that water can be circulatedfrom the reservoir into the compartment only when suction forces areeffected by the pump (FIG. 4). When the pump is stopped, the valveautomatically closes as illustrated in FIG. 3. Therefore, the migrationof the descaling agent into the reservoir can be avoided. The valve ispreferably a rubber-elastic valve comprising a membrane with a convexportion that is cut by at least one slit. For example, the valve takes aconvex shape for closing the flow path (FIG. 3) and a resilient concaveconfiguration for opening the flow path (FIG. 4). In the concaveconfiguration, the material of the valve is stretched so that the slitscan enlarge in an elastic manner allowing water to pass therethrough.This valve is usually known as a one-piece unidirectional valve or “slitvalve”, for example, sold by LMS company. The valve can be inserted in aseat 23 of the bottom of the reservoir.

The descaling agent can be any suitable descaling substance provided ina porous or water soluble/dispersible package such as a sachet and thelike or it may be a compacted tablet formed of the substance. Thedescaling agent may also be a liquid, gel or granules which fill aplastic compartment designed with a product release passage to free theliquid, gel or granules progressively as water circulates in thecompartment. For example, the compartment may comprise a venturi forsucking the descaling liquid and a mixing chamber for mixing it to waterin a suitable proportion. The descaling agent may also be encapsulatedin water soluble/dispersible capsules.

According to an aspect of the invention, the beverage preparation devicecan be programmed to operate a descaling cycle automatically upon thevalidation of a descaling command by the user. For example, the controlunit 11 comprises a descaling program which is operated by the push ofthe command button 130 on the keyboard 12. When the user presses thecommand, the control unit receiving the command signal from the board,runs the pump to start the descaling program. A water fill level sensor60 may be placed in the reservoir at a predetermined level to ensurethat the reservoir is properly filled with the required amount of water.If no signal from the fill level sensor is received by the control, thepump is not started and a proper alert signal 61 (e.g., a flashing led)may be sent to the board of the machine. Therefore, the user is promptedby the machine to fill the reservoir to the proper level before thestart of the descaling program. The reservoir may also comprise adescaling level which is materialized by, for instance, a visual mark onthe reservoir itself to indicate to the user how to properly fill thereservoir up. The control unit may also switch on the thermoblock forwarming the descaling liquid as it passes through it to increase thedescaling efficiency. The liquid may be warmed within a temperaturerange suitable for descaling, e.g., 45-60 degrees Celsius. The quantityof descaling agent in the compartment is determined to deplete or beentirely dissolved or be dispersed in less than all the quantity ofwater contained in the reservoir necessary for the full descalingprogram.

Preferably, the quantity of water to be filled in the reservoir for thefull descaling program must be such that still a sufficient quantity ofclear water in the reservoir is left and is circulated after all thedescaling agent is dispersed/dissolved in the descaling compartment.This principle is illustrated in FIG. 5. This graph shows the linearcurve 24 of the quantity of water that remains in the reservoir as afunction of time when the pump is running continuously withoutinterruption. On the same graph, one shows the depletion curve 25 of thedescaling agent in the compartment. A first phase 26 represents thedescaling phase. After about 10 minutes, the 18-grams mass of descalingagent has completely dissolved from the compartment as about a firstwater part corresponding to half of the 1-liter water reservoir has beenemptied. This phase is so followed by a rinsing phase 27 during whichthe remaining 500 Ml part of water in the reservoir is circulated in thefluid circuit. The descaling phase can be immediately followed by therinsing phase without intervention of the user since a sufficient waterpart remains in the reservoir for the rinsing phase. If an insufficientrinsing water level is detected in the reservoir at the end of thedescaling phase by the fill level sensor or flowmeter, the control unitmay stop the descaling operation and put the device in a stand-by modeuntil the reservoir is sufficiently replenished to reach the rinsinglevel. If the operation goes properly, the pump is automatically stoppedafter a certain quantity of water has been circulated. The user may bealerted on the keyboard that the procedure has gone successfully, by forinstance, a visual signal 61 (e.g, the led lighting continuously orwarning message).

For example, the control of the quantity of circulated water may notnecessarily be carried out by the control unit, in which case, water iscirculated until no more water is left in the water reservoir. Thecontrol procedure is therefore simplified.

In possible alternatives, the quantity of circulated water may becontrolled by different possible sensing means. The predeterminedquantity of circulated water can be controlled, for instance, by timingof the electrical supply of the pump. The water volume may also besensed by a flow meter placed at any location in the fluid circuit,e.g., on the second portion of hose 8 or integrated to the structure ofthe pump or heater. The volume of water may also be sensed by a filllevel sensor placed in the water reservoir. Of course, the pump may betemporally interrupted at certain intervals during a few seconds orminutes to provide soaking of the descaling liquid in the fluid circuit.

The descaling programs for running the descaling procedure can be storedin a read-only memory (ROM) and a random access memory (RAM) or othertypes of memories such as a programmable memory (EEPROM) connected to amicroprocessor of the control unit. The memories are configured forstoring relevant descaling parameters such as pause time, water level,flow rates, Ph value, etc. The control unit is arranged to managethrough interface units (e.g., I/O interface) the treatment of thesignals obtained from the sensors placed in the device (e.g., flowmeter, fill sensor, in-line Ph probe, etc.), the signals for managingthe control of the pump and water heater and the signals obtained fromthe keyboard.

As shown in FIG. 1, a collecting reservoir 28 may be needed at theoutlet of the beverage device. The collecting reservoir is placed by theuser before the descaling operation starts. In an alternative, the driptray of the machine is used as the drain reservoir.

FIG. 6 illustrates a variant of the beverage production device in whichthe descaling system comprises a compartment 30 for receiving thedescaling agent which is placed in the fluid circuit and fluidicallydistant from the water reservoir. In particular, the compartment forms abox which is fluidically linked to the water reservoir by an upstreamportion of hose 6A and which is fluidically linked to the pump 5 by adownstream portion of hose 6B. Therefore, water being aspirated by thepump flows through the upstream portion of hose 6A, then through thedescaling compartment via a water inlet, then through the downstreamportion of hose 6B via a water outlet of the compartment. The waterinlet and outlets can be placed on a same wall of the compartment ordifferent walls of the compartment. The compartment can comprise openingmeans such as a hinged portion of wall and locking means for enablingthe opening of the compartment and placing of a dose of descaling agent.The opening means are preferably designed to close the compartment in aliquid-tight manner with suitable sealing means to prevent water leakageout of the system/fluid circuit. The compartment can be placed in aconvenient access place of the machine such as in a drawer or in ahousing of the machine. The compartment may also be integrated as a partof the plastic cover of the machine.

In the embodiment of FIG. 6, the compartment may also advantageously bea removable cartridge containing a predose of a descaling substance. Inthis case, the compartment can be sealed to the external environmentwith only connecting means for connecting to the fluid circuit and maynot necessarily be provided with opening means. The cartridge can berecycled or discarded after depletion by the descaling procedure.

FIGS. 7 to 10 provide several examples of descaling programs from thesimplest one to a more sophisticated one, which can be stored in amemory of the control unit and processed by a processor the controlunit.

Referring to FIG. 7, after start of the device 80, a determination ismade whether the descaling command 130 has been pressed in step 81. Oncethe command has been pressed, the control unit 11 starts the pump instep 82 to start circulation of water from the reservoir through thefluid circuit. The descaling agent present in the compartment isprogressively dissolved/dispersed and the descaling phase runs. After apre-programmed time, the control unit stops the pump for a pause in step83. The descaling concentrated liquid is allowed to stay in the fluidcircuit for a programmed time. Then, in step 84, the control unit startsthe pump again until the water reservoir is emptied or during a fixedprogrammed time. This time is determined sufficiently long to enable thedescaling phase to end (i.e., the descaling agent being entirelydissolved in the in-line descaling system) and the rinsing phase to takeplace. The pump is then stopped and the procedure is so completed.

Referring to FIG. 8, the program contains in addition to the steps ofthe program of FIG. 7, the determination of a sufficient water level inthe water tank to ensure a proper rinsing with supposedly clear water inthe device. After the start 180, a determination is made to control ifthe descaling command has been pressed in step 181. If so, in step 182,the water level is sensed in the water reservoir 4 by the water fillprobe 60. In the next step 183, a test by the program is run in thecontrol unit to verify that the level of water corresponds to theprogrammed level. If the answer is “yes”, the control unit starts thepump in step 184 and the descaling procedure can commence. If the answeris “no”, the user is prompted to refill the water tank in step 188, forinstance by a led flashing on the control board of the device or by avisual message on a screen. When the tank has been refilled the programmay start again from step 181. If the descaling procedure has started,the next steps are the same as in the program of FIG. 7, i.e., one ormore pauses may be allowed in step 185 and the pump is run again in step186 for finishing descaling and then for rinsing the fluid circuit untilthe program stops the pump in step 187.

Referring to FIG. 9, the program contains a protocol for ensuring thatwater is present in the fluid circuit to ensure the complete descalingprocedure. Indeed, if the circuit runs out of water while descalingliquid is present in the circuit, there is a risk that the descalingagent stays too long in the circuit or that the liquid is accidentallyused for preparing a beverage. Therefore, after the start step 280, adetermination is made to control if the descaling command has beenpressed in step 281. If so, the control unit starts the pump in step282. In the next step 283, e.g., immediately after the pump is running,the flow rate is measured by the flow meter 50 in the fluid circuit andis compared in a test of the program in step 284 with a minimal valuestored in the memory of the control unit. If the measured value is lowerthan the store value, this indicates that there is no sufficient watercirculating in the fluid circuit and the pump is immediately stopped instep 285. If so, the user is prompted to refill the water reservoir instep 286 and the procedure starts again only when the descaling commandis pressed in step 281. If the measure flow rate value remainssufficiently high, the next steps consider the rinsing phase by runningthe pump in step 287 until the program ends in step 288. The flow ratedetermination and test of steps 282, 283 are run at periodical intervalin a loop to ensure a frequent control of presence of liquid in thecircuit. For example, the determination is done every 50 or 100milliseconds. Of course, several steps can be taken from the program ofFIG. 8 such as a predetermination of the fill level in the water tankand/or one or several pauses.

Finally referring to the program of FIG. 10, an acidity leveldetermination of the liquid in the fluid circuit is carried out by theprogram. This determination enables to stop the rinsing phase only whenthe water has reached an acceptable Ph level corresponding to anacceptable quality level of potable water. More precisely, after thestart step 380, a determination is made to control if the descalingcommand has been pressed in step 381. A determination of the water levelis carried out by the program in steps 382, 383, 384 in the same way asin the program of FIG. 8. After the level of water is found acceptablein the reservoir, the pump is started in step 385. The Ph level is thensensed in step 386 using an in-line Ph probe 85 located in the fluidcircuit, preferably, as close as possible to the beverage brewing point(FIG. 6). In step 387, the Ph sensed value is compared to a stored valuein the memory of the control unit and if this measured value is too low,the pump keeps running until the measured value reaches the storedvalue, in which case the pump is stopped and the program ends in step388. Of course, the Ph value which is stored in the memory may depend onthe hardness of the local water and may take into account a certaintolerance. Also, the stop of the pump may be delayed to let sufficientwater further rinse the circuit. Of course, many combinations of thedescribed programs can be envisaged. Of course, various signals and/ormessages can be displayed on the device for providing indication on thedifferent achieved steps during the procedure.

Of course, the device can be designed to run the descaling procedureremotely for instance if the device is equipped with a remote controlsystem communicating by wifi, internet and/or bluetooth. The descalingprogram may be part of a maintenance program which is stored in themachine or activated via said communication means from a remote computerincluding a laptop, mobile phone or palm.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. Method for descaling a beverage preparation machine automaticallyunder the control of a control unit of the machine comprising: placing adose of descaling agent in a compartment of the machine and filling areservoir with a predetermined quantity of water; circulating a firstpart of the predetermined quantity of water from the reservoir, in afluid circuit, whereby the descaling agent is dissolved or dispersedprogressively by water passing through the compartment to form descalingliquid circulating through heating means; and automatically circulatinga second or remaining part of the quantity of water from the reservoirin the fluid circuit through the heating means after the descaling agenthas dissolved or dispersed in the compartment to rinse the fluidcircuit.
 2. Method according to claim 1, wherein the first and secondparts of the quantity of water are automatically sequentially circulatedupon the user activating a descaling procedure's command and accordingto a descaling program of the control unit, without requiringintervention by the user.
 3. Method according to claim 2, wherein thedose of descaling agent and the quantity of water in the reservoir aredetermined so that a sufficient quantity of water is circulated from thereservoir to the module after the descaling agent is entirely dissolvedor dispersed from the compartment to rinse the fluid circuit.
 4. Methodaccording to claim 2, wherein during the first descaling phase, at leastone pause is provided to momentarily stop the circulation of water inthe fluid circuit.
 5. Method according to claim 1, wherein the waterlevel in the water tank is determined to verify that the reservoir isfilled with a sufficient quantity of water necessary for the descalingprocedure.
 6. Method according to claim 5, wherein the descalingprocedure is interrupted if the quantity of water in the reservoir isless than the quantity of water necessary for the descaling procedure.7. Method according to claim 1, wherein the acidity level of the waterin the fluid circuit is determined to verify the level of rinsing of thefluid circuit before ending the procedure.
 8. Method according to claim1, comprising collecting the circulated liquid in a collecting reservoirlocated at the beverage outlet.
 9. Method according to claim 1, whereinabout from ⅓ to ⅔ of the initial quantity of water is circulated fromthe reservoir for rinsing when the descaling agent is entirely dissolvedor dispersed.